1. Field of the Invention
This invention relates generally to a shaft adapter, and particularly to a shaft adapter useful for converting one shaft size to another to fit a variety of fan hub bore sizes and configurations.
2. Description of the Prior Art
A problem arises with the maintenance of refrigeration units and similar systems that employ cooling and air circulating fans. When a motor or blade of such a fan must be replaced, it is generally impractical for a serviceman to maintain a complete stock of all the different motors and blades that may be encountered. Accordingly, it is not unusual for a serviceman to carry only a single model replacement motor and associated fans for the commonly encountered capacity fan assemblies. Another situation is encountered where only the motor or blade of a fan assembly need be replaced and the shaft diameter and/or shaft length of the existing unit is different from the replacement fan motor or fan blade. Thus, it is desirable to have a shaft adapter which will permit the diameter of the shaft to be converted between that of the standard replacement motors and various other shaft diameters.
My copending, allowed application for U.S. patent, Ser. No. 718,039, entitled Shaft Adapter, and filed Aug. 26, 1976, discloses a shaft adapter which facilitates adaptation of a standard diameter motor shaft to another diameter, and also extends the length of the shaft to a user's requirements. Further, the shaft adapter disclosed in this copending application can be readily cut to proper size so as to eliminate surplus length of the adapter. A limitation on the possible use of my prior invention, however, is that the adapter cannot be readily employed with shafts and fan hubs having flat portions, or which employ set screws, keys, and the like.
U.S. Pat. No. 2,937,042, issued May 17, 1970, to S. Wilder, Jr., discloses a shaft coupling including a sleeve formed from a strip which forms a slot for receiving a key. This key, however, is merely employed to lock one shaft to another. Further, U.S. Pat. No. 2,807,485, issued Sept. 24, 1957, to L. H. Seibert, discloses a machine key arrangement wherein a cylindrical key provided with a slot for receiving a set screw helps retain a shaft on a hub, and the like, while U.S. Pat. No. 2,754,920, issued July 17, 1956, to E. H. Derry, discloses a reversible hub for a fan wherein a set screw is employed to help retain the fan hub on an associated shaft. In addition, U.S. Pat. No. 3,700,271, issued Oct. 24, 1972, to G. Blaurock, et al., discloses a tubular spacer ring for frictionally fastening a shaft in the oversized bore of a machine element, which arrangement is generally suitable only for larger equipment, and only practical for installation during manufacture of original equipment.